Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$177.34	9.723%	$194.5828	$194.58	$194.60	$194.60
Purchase #2	$63.73	12.698%	$71.8224	$71.82	$71.80	$71.80
Purchase #3	$6.42	12.589%	$7.2282	$7.23	$7.25	$7.20
Purchase #4	$41.39	4.807%	$43.3796	$43.38	$43.40	$43.40
Purchase #5	$193.95	7.492%	$208.4807	$208.48	$208.50	$208.50
Purchase #6	$142.85	8.647%	$155.2022	$155.20	$155.20	$155.20
Purchase #7	$53.93	6.773%	$57.5827	$57.58	$57.60	$57.60
7 purchase totals =	$679.61		$738.2786	$738.27	$738.35	$738.30